The category of Masters and Philosophers (zibu 子部) is the third of the four traditional categories (sibu 四部) into which Chinese literature was divided. The writings assembled in this category are quite heterogenous. Some are philosophical, others scientific, and a third part is a loose aggregation of descriptive notes. The term zi 子 is therefore not very easy to translate. The "masters and philosophers" were, during the Han period 漢 (206 BCE-220 CE), divided into Confucians (rujia 儒家), Mohists (mojia 墨家), sophists (mingjia 名家), legalists (fajia 法家), Yin-Yang thinkers (yinyangjia 陰陽家), theoreticians of the Five Progresses (wuxingjia 五行家), Daoists (daojia 道家), coalition advisors (zonghengjia 縱橫家), miscellaneous thinkers (zajia 雜家), agriculturalists (nongjia 農家) and novelists or storytellers (xiaoshuojia 小說家). Military theoreticians (bingjia 兵家) were in the beginning seen as a different group. With the growing amount of books written, the categories of astronomy and astrology (tianwen 天文), mathematics and calendar (lishu 曆數), as well as medical treatises (yifang 醫方) had to be incorporated into the literary categories. Technical skills were from the Tang period 唐 (618-907) on also part of the masters category. Later on, Buddhism was not any more a foreign religion, but Chinese monks started compiling Chinese treatises on Buddhism. At the same time the corpus of religious Daoist writings grew abundantly. The writings of the two religions had therefore also to be considered. Under the dominance of Confucian scholars, the two were always put at the end of the masters category and included only the most important writings. The collectaneaSiku quanshu 四庫全書 includes 2,984 books in this category.